Backport of #23090 to `release/2.29`.
When a user creates a workspace, opens the web terminal, then the
workspace stops but the web terminal remains open, the web terminal will
retry the connection. Coder would issue a HTTP 502 Bad Gateway response
when this occurred because coderd could not connect to the workspace
agent, however this is problematic as any load balancer sitting in front
of Coder sees a 502 and thinks Coder is unhealthy.
This PR changes the response to a HTTP 404 after internal discussion.
Cherry-picked from merge commit
c33812a430. The conflict in
`coderd/workspaceapps/errors.go` was resolved by applying the status
code change (502 → 404) while keeping the existing
`RetryEnabled`/`DashboardURL` fields (the `Actions` refactor is not on
this branch).
* chore: add /v2 to import module path
go mod requires semantic versioning with versions greater than 1.x
This was a mechanical update by running:
```
go install github.com/marwan-at-work/mod/cmd/mod@latest
mod upgrade
```
Migrate generated files to import /v2
* Fix gen
Rowan Smith